Liquid-crystal panel of polymer dispersed type, method of manufacturing the same, and liquid-crystal display apparatus

ABSTRACT

A liquid-crystal panel comprises a pair of transparent glass substrates each being provided with an electrode. Between the glass substrates are disposed spacers for defining a space and a mixture of droplets of a liquid crystal having a mean diameter of 3.0 μm or less and of a photo-curing polymer. The edge portions of the glass substrates are sealed with a seal polymer. In curing the photo-curing polymer during the process of manufacturing the liquid-crystal panel, the dose of an ultraviolet ray is set to 500 mJ/cm 2  or more so as to reduce the diameters of the droplets of the liquid crystal, thereby preventing light leakage in the state without a voltage applied and improving the contrast. If the spacers are colored, the effect of preventing light leakage is increased. If the spacers are subjected to a surface treatment for rejecting the liquid crystal or composed of a polymer material of the same type as that of the photo-curing polymer, variations in diameter of the droplets of the liquid crystal can be prevented. With the structure, it becomes possible to provide a liquid-crystal panel in which light leakage in the black mode is reduced and which presents uniform and high-contrast display of images.

This application is a continuation-in-part of application Ser. No.08/834,882 filed on Apr. 7, 1997, now abandoned, which is a continuationof application Ser. No. 08/361,550 filed Dec. 22, 1994, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to a liquid-crystal panel for use in aliquid-crystal display apparatus, an optical shutter, or the like, to amethod of manufacturing the same, and to a liquid-crystal displayapparatus using the liquid-crystal panel.

Liquid-crystal panels, which are small in size, light in weight, andoperable with low power voltage, have a wide range of applications asmeans for displaying a variety of visually recognizable patterns. Forexample, such appliances as wrist watches, electronic tabletopcalculators, personal computers, and personal word processors often useliquid-crystal panels therein for their further miniaturization andweight reduction. However, since a liquid-crystal panel of TN (twistednematic) type or STN (supertwisted nematic) type currently used requiresa polarizing plate, its light transmittance and long-term lightresistance are unsatisfactory. By contrast, since a panel containing apolymer dispersed liquid crystal (PDLC) does not require a polarizingplate, it is free from the above-mentioned drawbacks.

FIGS. 5(a) and 5(b) are cross-sectional views showing the structure of aconventional liquid-crystal panel of polymer dispersed type. FIG. 5(a)shows the state without a voltage applied, while FIG. 5(b) shows thestate with the voltage applied. As shown in FIGS. 5(a) and 5(b), theliquid-crystal panel is constituted by: a pair of glass substrates 1 aand 1 b having electrodes 2 a and 2 b, respectively, which are opposedto each other; and a mixture of a liquid crystal 4 and a photo-curingpolymer 5 which is filled into the space between the both substrates 1 aand 1 b. It is also possible to use a thermosetting polymer instead ofthe photo-curing polymer 5.

In a liquid-crystal panel of polymer dispersed type as described above,the liquid-crystal 4 is dispersed and held in the photo-curing polymer 5or the photo-curing polymer 5 exists in particles or in network in theliquid crystal 4. If a voltage is not applied to the space between theelectrodes 2 a and 2 b, liquid-crystal molecules are randomly orientedso that a difference in refractive index is caused between thephoto-curing polymer 5 and the liquid crystal 4, thereby scatteringlight (see FIG. 5(a)). On the other hand, if the voltage is applied tothe space between the electrodes 2 a and 2 b, the liquid-crystalmolecules are oriented in the direction of a resulting electric field sothat there is a match in refractive index between the liquid crystal 4and the photo-curing polymer 5, thereby transmitting light (see FIG.5(b)). Thus, the liquid-crystal panel of polymer dispersed type utilizesthe phenomena of light scattering and light transmission. Spacersdispersed between the substrates 1 a and 1 b in order to maintain aspecified distance therebetween are composed of an insulating materialin spherical particles. Specifically, spacers made of a transparentmaterial such as SiO₂, benzoguanamine resin, or melamine resin are usedat present.

However, the above conventional liquid-crystal panel is disadvantageousin that, when a voltage is not applied to the liquid-crystal panel,i.e., in the black mode, light scattering becomes unsatisfactory in thestate shown in FIG. 5(a), so that a sufficient contrast cannot beobtained. Even when the voltage is applied to the liquid-crystal panel,local variations are observed in light transmittance, resulting inuneven display of images.

In view of the foregoing, the present inventors have examined thephenomenon closely, which led to the following findings.

(1) The spacers composed of a transparent polymer material presents noproblem if they are used in the liquid-crystal panel of TN type or STNtype. However, if they are used in the liquid-crystal panel of polymerdispersed type which utilizes the phenomena of light scattering andlight transmission, light scattering becomes unsatisfactory when avoltage is not applied, i.e., in the black mode, so that a sufficientcontrast cannot be obtained.

(2) The use of spacers composed of an opaque colored polymer material,instead of a transparent material, is also under consideration asdisclosed in Japanese Laid-Open Patent Publication Nos. 63-157130,1-144021, and 4-15623. Even with the spacers composed of a coloredmaterial, however, it is difficult to obtain a sufficient contrast.

(3) When a phase separation is caused by irradiating the photo-curingpolymer with light or by heating the thermosetting polymer,liquid-crystal droplets adjacent to the spacers become larger in sizethan those not adjacent to the spacers. As a result, the application ofa voltage causes a difference in light transmittance between the regionsadjacent to the spacers and the other regions, so that a uniformdisplaying property may not be obtained in a liquid-crystal displayapparatus.

SUMMARY OF THE INVENTION

The present invention has been achieved in view of the foregoing and hasthe following objects.

The first object of the present invention is to provide a liquid-crystalpanel in which a difference in light transmittance between the statewith a voltage applied and the state without the voltage applied issignificant, i.e., a high-contrast liquid-crystal panel by usingliquid-crystal droplets and spacers with improved structures.

The second object of the present invention is to provide aliquid-crystal panel in which local variations in light transmittance inthe state with the voltage applied are reduced by using spacers with animproved structure.

The third object of the present invention is to provide a liquid-crystaldisplay apparatus with an excellent displaying property by using aliquid-crystal panel with excellent characteristics as described above.

To attain the above first object, a liquid-crystal panel with a firststructure comprises: a pair of substrates disposed so as to face eachother, each being provided with an electrode for applying a voltage;spacers dispersed in the space between the above pair of substrates soas to hold the above pair of substrates at a specified distance; apolymer member filled in the space between the above pair of substrates,and droplets of a liquid crystal mixed with the above polymer member andfilled in the space between the above pair of substrates, the abovedroplets of the liquid crystal having a mean diameter of 3.0 μm or less.

With the above first basic structure, since the liquid crystal to befilled in the space between the substrates in the liquid-crystal panelis in fine droplets, the function of scattering light when a voltage isnot applied is enhanced, so that light leakage via the droplets of theliquid crystal seldom occurs. Consequently, a high contrast can beobtained.

The above spacers can be provided with the function of preventing thetransmission of visible light. For this purpose, the spacers may becolored or the surface roughness of the spacers may be increased to adegree sufficient to scatter the visible light.

With the structure, light leakage via the spacers seldom occurs in theblack mode without the voltage applied, so that a higher contrast can beobtained.

To attain the above first object, a first method of manufacturing aliquid-crystal panel comprises the steps of: preparing in advance a pairof substrates each being provided with an electrode for applying avoltage and dispersing, on one of the above pair of substrates, spacersfor holding the substrates at a specified distance; holding the abovesubstrate on which the spacers are dispersed and the other substrate sothat they are opposed to each other with the spacers interposedtherebetween, mixing a prepolymer member with a liquid crystal, andfilling the mixture into the space between the substrates; and curingthe above prepolymer member while causing a phase separation between theabove polymer member and the above liquid crystal simultaneously, so asto separate the above liquid crystal in droplets having a mean diameterof 3.0 μm or less. If a photo-curing polymer is used as a material forcomposing the above polymer member, in particular, the above prepolymermember is irradiated with light equal to or intenser than 500 mJ/cm² inthe step of curing the above prepolymer member.

In the method, since the dose of light in the step of curing thephoto-curing prepolymer composing the polymer member has been set large,so that a distinct phase separation occurs between the liquid crystaland the polymer member. Consequently, the droplets of the liquidcrystal, which have been mixed with the polymer member, areminiaturized.

To attain the above second object, a liquid-crystal panel with a secondstructure comprises: a pair of substrates disposed so as to face eachother, each being provided with an electrode for applying a voltage; apolymer member filled in the space between pair of substrates, theabove; droplets of a liquid crystal mixed with the; and spacersdispersed in the space between the above pair of substrates so as tohold the above pair of substrates at a specified distance, the surfaceportions of the above spacers having at least either of a scarceaffinity with the droplets of the liquid crystal and a large affinitywith the above polymer member.

With the second structure, the effect of the liquid crystal moving faraway from the surfaces of the spacers becomes larger than the effect ofthe liquid crystal moving closer to the surfaces of the spacers.Consequently, during the phase separation caused by curing theprepolymer, the diameter of the droplet of the liquid crystal in aregion adjacent to the spacer does not become larger than the diameterof the droplet of the liquid crystal in a region not adjacent to thespacer. Accordingly, local variations in light transmittance of theliquid-crystal panel in the state with the voltage applied areminimized.

In a specific structure of the above liquid-crystal panel with thesecond structure, the surface portions of the spacers may be treated soas to have the property of rejecting the liquid crystal. Consequently,the liquid crystal is kept away from the surfaces of the spacers in theliquid-crystal panel, so that the diameter of the droplet of the liquidcrystal does not become particularly large in a region adjacent to thespacer.

In another specific structure, at least the surface portions of thespacers are composed of a polymer material of the same type as that ofthe above polymer member, with the result that the polymer memberpreferentially approaches the surfaces of the spacers. Consequently, thediameter of the droplet of the liquid crystal is not increased in aregion adjacent to the spacer.

It is also possible to add the above second structure to theliquid-crystal panel with the above first structure.

In the liquid-crystal panel with the above first or second structure, aphoto-curing polymer can be used.

With the structure, a phase separation is caused between the polymermember and the liquid crystal, so that an excellent dispersibility isimparted to the droplets of the liquid crystal.

A second method of manufacturing a liquid-crystal panel comprises thesteps of: preparing in advance a pair of substrates each being providedwith an electrode for applying a voltage and dispersing, on one of theabove pair of substrates; spacers for holding the substrates at aspecified distance, the surface portions of the above spacers havingeither a scarce affinity with droplets of a liquid crystal and a largeaffinity with a polymer member; holding the above substrate on which thespacers are dispersed and the other substrate so that they are opposedto each other with the spacers interposed therebetween, mixing aprepolymer member with a liquid crystal, and filling the mixture intothe space between the substrates; and curing the above prepolymer memberand forming said polymer member, while causing a phase separationbetween the above polymer member and the above liquid crystalsimultaneously.

Specifically in the above second method of manufacturing aliquid-crystal panel, a surface-active agent containing fluorine as itsmain component is adsorbed by the surfaces of the spacers so that thesurface portions of the spacers have the property of rejecting the aboveliquid crystal or the spacers at least the surface portions of which arecomposed of a material of the same type as that of the above polymermember are used.

With the above method, the liquid-crystal panel with the secondstructure can be obtained.

To attain the above third object, the liquid-crystal display apparatusof the present invention comprises in addition to the liquid-crystalpanel with the above first or second structure: light radiating meansfor irradiating the liquid-crystal panel with light; a driving circuitfor applying an electric signal to the above liquid-crystal panel; and adisplaying means for displaying the pattern of light outputted from theabove liquid-crystal panel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view diagrammatically showing the structureof a liquid-crystal panel according to a first embodiment;

FIG. 2 is a flow chart showing the process of manufacturing theliquid-crystal panel according to the first embodiment;

FIG. 3 is a cross-sectional view diagrammatically showing the structureof the liquid-crystal panel according to a fifth embodiment;

FIG. 4 is a block diagram schematically showing the structure of aliquid-crystal display apparatus according to a sixth embodiment;

FIG. 5(a) is a cross-sectional view diagrammatically showing thephenomenon of light scattering caused by a polymer dispersed liquidcrystal when a voltage is applied thereto; and

FIG. 5(b) is a cross-sectional view diagrammatically showing thephenomenon of light transmission caused by the polymer dispersed liquidcrystal when the voltage is not applied thereto.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(First Embodiment)

Below, a first embodiment of the present invention will be describedwith reference to the drawings.

FIG. 1 shows a liquid-crystal panel according to the first embodiment,which comprises: a pair of transparent glass substrates 1 a and 1 bopposed to each other; a pair of electrodes 2 a and 2 b provided on therespective inner surfaces of the glass substrates 1 a and 1 b so as toface each other; spacers 3 interposed between the glass substrates 1 aand 1 b so as to hold the electrodes 2a and 2b at a specified distance;a liquid-crystal/polymer composite 6 composed of a liquid crystal 4 anda photo-curing polymer 5 to be introduced into the space between theglass substrates 1 a and 1 b; and a seal polymer 7 for sealing the edgeportions of the liquid-crystal panel.

Below, a description will be given to a method of manufacturing theliquid-crystal panel according to the first embodiment with reference tothe flow chart of FIG. 2.

On the pair of transparent glass substrates 1 a and 1 b arepreliminarily formed the transparent conductive films (ITO films) 2 aand 2 b, each serving as an electrode. After cleaning the glasssubstrates 1 a and 1 b in Step ST1, spherical particles of SiO₂, eachhaving a diameter of 13 μm and colored with black, are dispersed as thespacers 3 on the electrode 2 a of the glass substrate 1 a in Step ST2,while the seal polymer 7 is printed on the edge portions of the otherglass substrate 1 b in Step ST3. These glass substrates 1 a and 1 b arebonded together with the spacers 3 and seal polymer 7 interposedtherebetween in Step ST4. The seal polymer 7 is cured in Step ST5 withthe application of heat.

Subsequently, in Step ST6, a mixture of the liquid crystal 4 (which willbe turned into droplets later on) and an ultraviolet-curing polymer,which is a type of photo-curing polymer, is injected into the spacebetween the glass substrates 1 a and 1 b. The components of the mixtureare as follows:

liquid crystal E-7 (commercially available from British Drug House Ltd.)(80 wt %) ultra-violet curing polymer mixture of polyester acrylate (1.8wt %) and 2-ethylhexyl acrylate (18 wt %) photopolymerization initiatorDarocur-1173 (commercially available from Merck Ltd.) (0.2 wt %)

Next, in Step ST7, the liquid-crystal panel after injection isirradiated with an ultra-violet (UV) ray, thereby inducing apolymerizing reaction in the photo-curing polymer 5. The polymerizingreaction in turn causes a phase separation between the liquid crystal 4and the photo-curing polymer 5 so that droplets of the liquid crystal 4are dispersed in the photo-curing polymer 5, while the photo-curingpolymer 5 is cured simultaneously. Thereafter, an injection hole issealed in Step ST8, thus completing the fabrication of theliquid-crystal panel.

Next, a description will be given to a test performed in order toelucidate the relationship between the doze of light for thephoto-curing polymer 5 and the mean diameter of the droplets of theliquid crystal 4.

Liquid-crystal panels were fabricated in accordance with the procedureshown in FIG. 2. In this case, the dose of an ultra-violet ray for thephoto-curing polymer 5 was varied and set to 100, 200, 300, 400, 500,1000, and 2000 mJ/cm² for the respective liquid-crystal panels. Forcomparison, there was fabricated another liquid-crystal panel in whichcolorless and transparent particles of SiO₂ were scattered as thespacers.

These liquid-crystal panels were examined using a microscope and it wasobserved that the mean diameter of the droplets of the liquid crystal 4in the liquid panel irradiated with an ultraviolet ray of 400 mJ/cm² orless in the curing step was as large as 5.5 μm or more, while the meandiameter of the liquid-crystal droplets in the liquid-crystal panelirradiated with an ultraviolet ray of 500 mJ/cm² or more in the curingstep was as small as 1.0 to 3.0 μm. The contrasts of the liquid-crystalpanels and the mean diameters of the droplets of the liquid crystal 4therein were measured, the results of which are shown below in Table 1.

TABLE 1 COLOR- DOSE OF LESS ULTRA- TRANS- VIOLET PARENT RAY SPACER BLACKSPACER (mJ/cm²) 500 100 200 300 400 500 1000 2000 CONTRAST 53 25 37 4651 98 108 110 MEAN 2.4 15.4 10.7 8.2 5.5 2.4 1.7 1.0 DIAMETER OF LIQUID-CRYSTAL DROPLETS (μm)

It can be appreciated from the above Table 1 that the liquid-crystalpanel using the colorless and transparent spacers is low in contrast andunsatisfactory in the black mode compared with the liquid-crystal panelusing the colored spacers. For example, if the liquid-crystal panelusing the black spacers and the liquid-crystal panel using thetransparent spacers are irradiated with the same ultraviolet ray of 500mJ/cm², the liquid-crystal panel with the black spacers presents a highcontrast of 98, while the liquid-crystal panel with the transparentspacers has a low contrast of 53. This may be because light leakage inwhich the spacer transmits light occurs in the black mode without avoltage applied.

The same tendency can be recognized even when the mean diameter of thedroplets of the liquid crystal 4 is small. That is, if theliquid-crystal panels using the black spacers are compared with eachother, the mean diameter of the droplets of the liquid crystal becomeslarger as the dose of the ultraviolet ray is reduced. For example, ifthe dose of the ultraviolet ray is 500 mJ/cm², the diameters of thedroplets of the liquid crystal are surely 3.0 μm or less and thecontrast obtained is as large as 98 or more. By contrast, if the dose ofthe ultraviolet ray is 400 mJ/cm² or less, the mean diameter of thedroplets of the liquid crystal is as large as 5.5 μm or more and thecontrast obtained is as small as 51 or less. This may be because thelight leakage via the droplets of the liquid crystal 4 occurs in theblack mode, since the mean diameter of the droplets of the liquidcrystal 4 is large.

On the other hand, if the black spacers are used and the dose of theultraviolet ray is increased so that an ultraviolet ray of 500 mJ/cm² ormore is applied in the curing step, a distinct phase separation occursbetween the liquid crystal 4 and the photo-curing polymer 5, so that themean diameter of the droplets of the liquid crystal 4 becomes as smallas 3.0 μm or less. Consequently, light leakage via the droplets of theliquid crystal 4 or via the spacers 3 hardly occurs in the black mode.

Even when the transparent spacers are used, if an ultraviolet ray of 500mJ/cm² is applied, the contrast obtained is higher than the contrastobtained in the case where the black spacers are used but only anultraviolet ray of 100 mJ/cmz is applied (53 versus 25). Hence, it canbe concluded that a mere reduction in size of the droplets of the liquidcrystal 4 is effective to a certain degree in raising the contrast.

(Second Embodiment)

Next, a second embodiment will be described.

The structure of the liquid-crystal panel in the second embodiment issubstantially the same as the structure of the liquid-crystal panel inthe above first embodiment of FIG. 1, except that the spacer 3 in thepresent embodiment is not spherical, but in the shape of a rod having adiameter of 10 μm and a length of 50 μm, though the drawing thereof isomitted here. The rod-shaped spacer 3 is composed of a glass fibercolored with black. As for the other components, the structures thereofare the same as those shown in FIG. 1.

A voltage was applied to the liquid-crystal panel thus fabricated andthe contrast and the mean diameter of the droplets of the liquid crystal4 were measured, the results of which are shown below in Table 2.

TABLE 2 COLOR- DOSE OF LESS ULTRA- TRANS- VIOLET PARENT RAY SPACER BLACKSPACER (mJ/cm²) 500 100 200 300 400 500 1000 2000 CONTRAST 53 21 29 4149 88 93 95 MEAN 2.4 21.0 14.3 9.1 6.2 3.0 2.6 2.0 DIAMETER OF LIQUID-CRYSTAL DROPLETS (μm)

In Table 2 is also shown the contrast of a liquid-crystal panel usingcolorless and transparent spacers for comparison with the liquid-crystalpanel according to the present embodiment. It will be appreciated fromTable 2 that, even when the rod-shaped spacers are disposed as in thepresent embodiment, the liquid-crystal panel using the black spacers andirradiated with an ultraviolet ray of 500 mJ/cm² or more in the curingstep presents an excellent contrast of 88 or more.

Although the spacers were colored so that they function as means forpreventing the transmission of visible light in the above first andsecond embodiments, the present invention is not limited to theseembodiments. If the surface roughness of the spacers is increased, lightis scattered by the surfaces of the spacers so that light leakage viathe spacers in the black mode can be prevented effectively.

(Third Embodiment)

Next, a third embodiment will be described.

The structure of the liquid-crystal panel in the third embodiment isbasically the same as the structure of the liquid-crystal panel in theabove first embodiment (see FIG. 1), except that the surface of thespacer 3 shown in FIG. 1 is treated so as to adsorb a surface-activeagent containing fluorine as its main component. The spacer itself is ablack spherical particle of SiO₂ having a diameter of 13 μm and has thesame structure as that of the spacer 3 used in the above firstembodiment.

The process of manufacturing the liquid-crystal panel in the presentembodiment is obtained by providing the steps shown in FIG. 2 with anadditional step of treating the surface of the spacer 3, though thedrawing thereof is omitted here.

Next, a description will be given to the manufacturing process based ona test performed in order to elucidate the relationship between thepresence or absence of the surface treatment for the spacers and themean diameter of the droplets of the liquid crystal 4.

The liquid-crystal panels were fabricated in accordance with theprocedure shown in FIG. 2. In each of the liquid-crystal panels, theglass substrates 1 a and 1 b, electrodes 2 a and 2 b, spacer 3, liquidcrystal 4, photo-curing polymer 5, and seal polymer 7 are made of thesame materials as used in the above first embodiment. In the presenttest, however, the dose of the ultraviolet ray for the ultra-violetcuring polymer was changed to 1500 mJ/cm² and two types of spacers 3,one with the surface treatment for absorbing the surface-active agentcontaining fluorine as its main component and the other without thesurface treatment, were used for comparison. In either case, thematerial and configuration of the spacers are the same and the spacersare composed of black spherical particles of SiO₂. The surface portionsof the spacers have the property of rejecting a liquid crystal, impartedto the spacers by surface treatment in which a surface-active agentcontaining fluorine as its main component is absorbed by the surfaces ofthe spacers.

These liquid-crystal panels were examined using a microscope. In theliquid-crystal panel using the spacers without the surface treatment,the diameter of the liquid-crystal droplet in a region not adjacent tothe spacer was about 1.5 μm, while the diameter of the liquid-crystaldroplet in a region adjacent to the spacer was about 4.5 μm, which wassubstantially tripled. On the other hand, in the liquid-crystal panel ofthe present embodiment with the surface treatment using thesurface-active agent containing fluorine as its main component, it wasrecognized that the diameters of the liquid-crystal droplets in a regionadjacent to the spacer as well as in a region not adjacent to the spacerare of the same order (about 1.0 μm) and uniform. A voltage was appliedto these liquid-crystal panels so that their respective displayingproperties were compared with each other. As a result, theliquid-crystal panel using the spacers with the surface treatment of thepresent embodiment excellently presented a uniform displaying property,while uneven display of images was observed in the conventionalliquid-crystal panel without the surface treatment.

(Fourth Embodiment)

Next, a fourth embodiment will be described.

In the present embodiment also, the basic structure of theliquid-crystal panel and the materials of the individual componentsthereof are the same as described in the above first embodiment (seeFIG. 1), except that the spacers 3 in the liquid-crystal panel of thepresent embodiment are composed of a polymer material of acrylic system,which is of the same type as that of the photo-curing polymer 5composing the liquid-crystal/polymer composite 6.

A voltage was applied to the liquid-crystal panel so that its displayingproperty was compared with the displaying property of the conventionalliquid-crystal panel with colorless and transparent particles of SiO₂dispersed therein. As a result, the liquid-crystal panel of the presentembodiment excellently presented a uniform displaying property, whileuneven display of images was observed in the conventional liquid-crystalpanel.

(Fifth Embodiment)

Next, a fifth embodiment will be described.

FIG. 3 is a cross-sectional view diagrammatically showing the structureof the liquid-crystal panel in a fifth embodiment. In the presentembodiment, the spacer 3 consists of a main body 3 a composed of a SiO₂particle and a surface portion 3 b for covering up the SiO₂ particleforming the main body 3 a. The surface portion 3 b is composed of apolymer of acrylic system, similarly to the photo-curing polymer 5. Thatis, unlike the above fourth embodiment, only the surface portion of thespacer 3 is composed of a polymer material of the same type as that ofthe photo-curing polymer 5. The structures of the other components ofthe liquid-crystal panel according to the present embodiment are thesame as those shown in FIG. 1.

A voltage was applied to the liquid-crystal panel so that its displayingproperty was compared with the displaying property of the conventionalliquid-crystal panel. As a result, the liquid-crystal panel of thepresent embodiment excellently presented a uniform displaying property,while uneven display of images was observed in the conventionalliquid-crystal display.

(Sixth Embodiment)

Below, a sixth embodiment will be described.

FIG. 4 is a block diagram schematically showing the structure of aliquid-crystal display apparatus according to the sixth embodiment. Asshown in the drawing, the liquid-crystal display apparatus according tothe present embodiment comprises; a light source 11 composed of a metalhalide lamp; a UV/IR cutting filter 12; and three optical systems fordisplaying three colors, which are placed behind the light source 11 andUV/IR cutting filter 12. The three optical systems consist of dichroicmirrors 13 a, 13 b, and 13 c, liquid-crystal panels 14 a, 14 b, and 14c, lenses 15 a, 15 b, and 15 c, apertures 16 a, 16 b, and 16 c, andprojecting lens systems 17 a, 17 b, and 17 c. Each of the liquid-crystalpanels 14 a, 14 b, and 14 c is connected to a driving circuit, thoughthe drawing thereof is omitted here. The above three liquid-crystalpanels 14 a, 14 b, and 14 c use black spacers and were fabricated bysetting the dose of an ultraviolet ray in the step of curing thephoto-curing polymer to 2000 mJ/cm² so that the mean diameter of thedroplets of the liquid crystal becomes 1.0 μm.

Light from the light source (metal halide lamp) 11 is transmitted by theUV/IR cutting filter 12 and then separated into blue color, green color,and red color by the dichroic mirrors 13 a, 13 b, and 13 c, which areincident upon the liquid-crystal panels 14 a, 14 b, and 14 c,respectively. After passing through the lenses 15 a, 15 b, and 15 c andthrough the apertures 16 a, 16 b, and 16 c, the three colors areincident upon the projecting lens systems 17 a, 17 b, and 17 c. When animage was projected with the use of the apparatus, excellenthigh-contrast display was obtained.

In addition, liquid-crystal panels using black spacers, in which thedose of the ultra-violet ray in the step of curing the photo-curingpolymer was set to 500 mJ/cm² and to 1000 mJ/cm², were fabricated andliquid-crystal display apparatus using the liquid-crystal panels werefabricated. In this case also, excellent displaying properties wereobtained. Similarly excellent displaying properties were also obtainedin the case where liquid-crystal display apparatus were formed by usingthe liquid/crystal panels with the structures of the above second tofifth embodiments.

It is not necessary for each of the pair of substrates disposed in theliquid-crystal panel of the present invention to be transparent. It issufficient for at least one of the substrates to be transparent. Theliquid-crystal display apparatus may have reflecting lens systems inplace of the projecting lens systems.

Although the mixture of polyester acrylate and 2-ethylhexyl acrylate wasused in each of the above embodiments, it is also possible to use2-hydroxylethyl acrylate, trimethylol-propane-triacrylate, and the like.It is also possible to use a thermosetting polymer, instead of thephoto-curing polymer, so that it reacts with the application of heat. Ifa thermosetting polymer of novolac system is used in this case,hexamethylenediamine (hexamine) can be used as a curing agent.

The liquid crystal can be E-8 (commercially available from British DrugHouse Ltd.), ZLI4792 (commercially available from Merck Ltd.), TL202(commercially available from Merck Ltd.), or the like. Thepolymerization initiator can be Irgacure 184 (commercially availablefrom Chiba-Geigy Ltd.), Irgacure 651 (commercially available fromChiba-Geigy Ltd.), or the like.

In other words, the present invention is effective irrespective of theliquid-crystal material and polymer material used.

A surface reforming agent for treating the surface of the spacer is notlimited to the surface-active agent containing fluorine as its maincomponent. A silane coupling agent (e.g., KA1003, KBC1003, KBE1003,KBM1003, KBM503, KBM303, KBM403, KBE402, KBM603, KBM602, KBE903, KBM573,KBM603, or KBM703, each commercially available from Shinetsu ChemicalCo., Ltd.; A-143, A-150, A-151, A-171, A-172, A-174, A-186, A-187,A-189, A-1100, A-1120, or A-1160, each commercially available fromNIPPON UNICAR Co., Ltd.; or SH6020, SZ6023, SH6026, SZ6030, SZ6032,SH6040, SZ6050, SH6062, SZ6070, SZ6072, SH6075, SH6076, SZ6079, SZ6083,SZ6300, AY43-021, PRXll, PRX19, or PRX24, each commercially availablefrom Toray Silicone Co., Ltd.), a silicone surface-active agent (e.g.,L-77, L-720, L-722, L-5310, L-7001, L-7002, L-7500, L-7600, L-7602,L-7604, L-7607, or Y-7006, each commercially available from NIPPONUNICAR Co., Ltd.), a silane monomer (e.g., A-162 or A-163, eachcommercially available from NIPPON UNICAR Co.,), a silicone primer(e.g., AP-133, Y-5106, Y-5254, or APZ-6601, each commercially availablefrom NIPPON UNICAR Co.,), a coupling agent of titanate system (e.g.,PLENACT, KRTTS, KR38S, KR44, KR46B, KR55, KR138SS, KR238S, 338X, KR2S,KR7, KR9S, KR11, KR12, KR34S, or KR41B, each commercially available fromAJINOMOTO CO., INC.), a coupling agent of aluminum system (e.g., AL-Mcommercially available from AJINOMOTO CO., INC.), a surface-active agentof amino acid system (e.g., AMISOFT or CAE, each commercially availablefrom AJINOMOTO CO., INC.), an agent for homeotropic orientation (e.g.,DMOAP or ODS-E, each commercially available from Chisso Corporation), orthe like is also effective. If colored spacers are subjected to thesurface treatment, light leakage in the state without the voltageapplied is eliminated, so that the contrast is further improved.

To color the spacers, there can be used any of the method of coloring bymeans of a dye, the method of having an organic substance adsorbed intominute holes in the spacers so that it is carbonized by sintering, themethod of sputtering fine black particles into the spacers, and thelike.

It is also possible to use an active-matrix substrate composed of activeelements provided on one of the electrode substrates.

We claim:
 1. A liquid-crystal panel of polymer dispersed typecomprising: a pair of substrates disposed so as to face each other, eachbeing provided with an electrode for applying a voltage; a polymermember filled in the space between said pair of substrates; droplets ofa liquid crystal mixed with said polymer member and filled in the spacebetween said pair of substrates; and spacers dispersed in the spacebetween said pair of substrates so as to hold said pair of substrates ata specified distance, surface portions of said spacers having at leasteither of a scarce affinity with the droplets of the liquid crystal or alarge affinity with said polymer member.
 2. A liquid-crystal panel ofpolymer dispersed type according to claim 1, wherein the surfaceportions of said spacers are treated so as to reject said liquidcrystal.
 3. A liquid-crystal panel of polymer dispersed type accordingto claim 1, wherein at least the surface portions of said spacers arecomposed of a polymer material of the same type as that of said polymermember.
 4. A liquid-crystal display apparatus comprising: aliquid-crystal panel of polymer dispersed type; a light radiating meansfor irradiating said liquid-crystal panel with light; a driving circuitfor applying an electrode signal to said liquid-crystal panel; and adisplaying means for displaying the patterns of light outputted fromsaid liquid-crystal panel, wherein said liquid-crystal panel comprises:a pair of substrates disposed so as to face each other, each beingprovided with an electrode for applying a voltage; a polymer memberfilled in the space between said pair of substrates; droplets of aliquid crystal mixed with said polymer member and filled in the spacebetween said pair of substrates; and spacers dispersed in the spacebetween said pair of substrates so as to hold said pair of substrates ata specified distance, the surface portions of said spacers having atleast either of a scarce affinity with the droplets of the liquidcrystal or a large affinity with said polymer member.
 5. Aliquid-crystal panel comprising: a pair of substrates disposed so as toface each other, each being provided with an electrode for applying avoltage; spacers dispersed in a space between said pair of substrates soas to hold said pair of substrates at a specified distance, said spacershaving a function of preventing transmission of visible light and havinga surface roughness sufficiently high to scatter visible light; apolymer member filled in the space between said pair of substrates; anddroplets of a liquid crystal mixed with said polymer member and filledin the space between said pair of substrates, said droplets of theliquid crystal having a mean diameter of 3.0 μm or less.
 6. Aliquid-crystal panel of polymer dispersing type comprising: a pair ofsubstrates disposed so as to face each other, each being provided withan electrode for applying a voltage; spacers dispersed in a spacebetween said pair of substrates so as to hold said pair of substrates ata specified distance; a polymer member filled in the space between saidpair of substrates, wherein surface portions of said spacers have atleast either a scarce affinity with the droplets of the liquid-crystalor a large affinity with said polymer member; and droplets of a liquidcrystal mixed with said polymer member and filled in the space betweensaid pair of substrates, said droplets of the liquid crystal having amean diameter of 3.0 μm or less.
 7. A liquid-crystal panel of polymerdispersed type according to claim 6, wherein the surface portions ofsaid spacers are treated so as to have the property of rejecting saidliquid crystal.
 8. A liquid-crystal panel of polymer dispersed typeaccording to claim 6, wherein at least the surface portions of saidspacers are composed of a polymer material of the same type as that ofsaid polymer member.
 9. A liquid-crystal panel of polymer dispersed typecomprising: a pair of substrates disposed so as to face each other, eachbeing provided with an electrode for applying a voltage; spacersdispersed in a space between said pair of substrates so as to hold saidpair of substrates at a specified distance, said spacers being coloredand having a surface roughness sufficiently high to scatter visiblelight; a polymer member filed in the space between said pair ofsubstrate; and droplets of a liquid crystal mixed with said polymermember and filled in the space between said pair of substrates, saiddroplets of the liquid crystal having a mean diameter of 3.0 μm or less.10. A liquid-crystal panel of polymer dispersed type comprising: a pairof substrates disposed so as to face each other, each being providedwith an electrode for applying a voltage; spacers dispersed in a spacebetween said pair of substrates so as to hold said pair of substrates ata specified distance, said spacers being colored and having surfaceportions; a polymer member filed in the space between said pair ofsubstrates wherein the surface portions of said spacers have at leasteither of a scarce affinity with the droplets of the liquid-crystal or alarge affinity with said polymer member; and droplets of a liquidcrystal mixed with said polymer member and filled in the space betweensaid pair of substrates, said droplets of the liquid crystal having amean diameter of 3.0 μm or less.